1. Technical Field
The invention relates to a guide apparatus, and in particular, to an apparatus for guiding a strip of material to a tire-building drum. More particularly, the invention relates to a guide apparatus which maintains a material strip centered as it moves through the apparatus for accurate placement and alignment of the strip on an adjacent tire-building drum. Even more particularly, the invention relates to a lock-out device incorporated into the guide apparatus for temporarily moving spaced guiding elements out of engagement with the strip until the strip is centered with respect to the tire-building drum.
2. Background of the Invention
Apparatus of the type in which the present invention is incorporated, is generally referred to in the tire-building art as a "server" or "guide", and typically includes a flat table or plate which is positioned in operative position adjacent a tire-building drum. On the upper surface of the guide plate or table are transversely movable guide members or rails selectively adjustable to various predetermined spacings established by the width of the particular flat tire component strip being applied to the drum.
Heretofore, these guide rails or guide members have been moved transversely to the surface of the guide plate by various mechanisms. For example, in U.S. Pat. No. 1,711,074, a shaft and drive sprocket has been provided with detent fingers extending radially of the shaft and selectively engaged in a spring detent fixed to a support plate. Manual rotation of the sprocket shaft would move from one position to the next, thus establishing a desired number of preselected locations for the spaced guide members.
U.S. Pat. No. 3,170,829 shows another guide apparatus for a tire-building machine which uses a chain drive linkage for setting the spacing between the guide rails or fences. Coil springs are used to bias the guides away from each other and toward an outward position out of engagement with the strip material being conveyed therebetween. The guide fence members are in engagement with a latch bar, and one or more control stops are positioned, such that the latch bar will engage the control stop to position the guide fence members for different widths of tire components.
U.S. Pat. No. 3,269,627 shows another type of guide mechanism which is used for hot strip material in which the two spaced fences and guides are moved by a piston cylinder assembly and a rotatable shaft for adjusting the position between the two guides.
U.S. Pat. No. 4,750,660 discloses another guide apparatus for sheet or strip material in which the guide rails are positioned by a rotatable threaded shaft and guide rails, and a positioning cylinder for setting the desired spacing between the rails. A lock mechanism is provided for the piston rods to secure the sheet guides in a specific position. The lock mechanism may be pneumatic, electromagnetic, or other convenient arrangement. Preset blocks are positioned by the engagement of expandable portions of the air cylinders with the engagement portions of the block, which prevent the preset blocks from being repositioned after the air cylinders disengage the engagement positions.
U.S. Pat. No. 4,961,813 shows a guide mechanism for sheet or strip material for a tire-building drum in which the spacing between the guide members is achieved by a drive belt and drive motor. Rollers, which are located adjacent to the edges of the conveyor, are used to shift the leading edge of the strip material toward the longitudinal centerline of the conveyor. A motor and belt will enable the rollers to be positioned with respect to the strip material, and sensors determine the width of the strip material and enable the motor to adjust accordingly.
Although these prior guide devices and apparatus provide for the accurate setting of the guide fences or rails, they do not provide for the automatic simultaneous adjustment of the guide rails in order to compensate for increased or decreased strip widths which can occur in many strip components while being fed to a tire-building drum. This can result in the moving strip being moved off-center, and, therefore, inaccurately delivered to the tire-building drum. As the complexity of the tire structure has increased, the necessity for extreme accuracy in positioning the guide members or guide rails for delivery of the tire strip component has become more critical, especially when used with automated tire-making equipment.
Many of the above problems are overcome by the guide apparatus described in co-pending application Ser. No. 08/388,705, which is assigned to the same assignee as the present invention. In this apparatus, a spring or weight-biasing mechanism provides a constant biasing force on the strip-engaging rollers mounted on the spaced guide rails. The biasing force enables the guide rails to automatically compensate for various width changes, both increases and decreases, in the strip.
One problem that arises when utilizing guide devices which include such a spring- or weight-biased mechanism for maintaining the strip centered, as described in the above-referenced pending patent application, is that the biasing force on the rollers will force the tip of a strip of material which has a leading edge cut at an angle off-center. This is due to the fact that the biasing rollers will initially engage only one longitudinal edge of the strip until the front angled end has passed beyond the rollers, after which the biasing force of the guide rollers apply equal force to both longitudinal edges of the strip.
None of the prior guide devices and apparatus discussed above provide any device for temporarily disengaging a biasing mechanism which exerts a centering force on the strip edges until the strip material is properly set on the tire-building drum.
Therefore, the need exists for a guide apparatus used primarily with a tire-building drum, which apparatus includes a device which temporarily removes the biasing force exerted by the guide rollers on the edges of the strip until a leading angled end of the strip has been accurately positioned on a tire-building drum, after which the device will enable the biasing force to be reapplied on the guide rails to automatically compensate for variations in strip width as the strip moves toward the tire-building drum and through the server to maintain the strip centered in the server to provide accurate delivery to the tire-building drum.